A thread on NeoGAF
notes some code in the new Steam beta suggesting Valve is planning to allow
Steam users to select games to share with a circle of friends. This is confirmed
on
Kotaku, where they say Valve has not yet responded to the report (not a
shock since their story went up at 3:00 am on the west coast). Here is the code
in question:

"SteamUI_JoinDialog_SharedLicense_Title" "Shared game
library"
"SteamUI_JoinDialog_SharedLicenseLocked_OwnerText" "Just so you know, your games
are currently in use by %borrower%. Playing now will send %borrower% a notice
that it's time to quit."
"SteamUI_JoinDialog_SharedLicenseLocked_BorrowerText" "This shared game is
currently unavailable. Please try again later or buy this game for your own
library."

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When Steam finally stops asking if I 'want' to go on-line when I am offline and when Steam stops taking focus from the game app during app start and when Steam no longer requires an administrative level Windows™ service for its use, then Steam will be trying to gain me as a customer. Until then what it offers isn't really worth sharing or sharing at all.